In order to cast as broad a net as possible, for all possible name matches, CRIS limits the number of search parameters to Last Name, First Name and a Year of Birth (not date of birth) box. It is recommended that the Year of Birth parameter be used as sparingly as possible in order to avoid the danger of missing a record that uses a different YOB (for various reasons like human data entry error, incorrect user information, etc.) or a non-existant date of birth.
Since some AOC databases do not provide birth dates it is recommended that the YOB not be used in AOC searches, unless you want to omit records which do not have birthdates.